1. Field of the Invention
The present invention is directed to optical pointing mechanisms and, more specifically, to a pointing mechanism utilizing linear actuators to achieve independent gimballing of an optical concentrator and the focal point equipment in an extraterrestrial environment.
2. Prior Art
Prior state-of-the-art pointing mechanisms point, or move the entire optical package or system en masse. This means that the target or source is rigidly attached to the lens or reflector (optical concentrator). The pointing mechanism is attached to the reflector or lens, usually on the side or back of the reflector or lens. The pointing accuracy required by the target or source is obtained only through the use of this single mechanism.
This is adequate on earth under normal circumstances because the stiffness required in the support structure between the optical element and the target or source is inexpensive in terms of direct and indirect cost. The direct cost is the cost of the material and labor to fabricate the structure. The indirect cost is the cost of the effect of the structure on the rest of the system, such as power to point the system and the cost of the system support structure, foundation or transportation.
In space the indirect costs become extremely important and often drive the system costs. For Radio Frequency (RF) applications the source or target is a low-mass item. Consequently, the indirect cost penalty of the structure between the source/target and the optical element is not significant. Consequently, the cost of implementing prior art pointing mechanisms is not high for RF space applications.
However, for systems employing a heavy source or target, the indirect costs become prohibitive. For example, in the case of solar dynamic power systems, the primary impact of the indirect cost of employing prior art pointing mechanisms is in the moment of inertia impact on the space vehicle.